Wound dressings, consisting of a urethane film having adhesive on one side for carrying an absorbent pad and adhering to a patient's skin surrounding an open wound, are known in the art. The flexible nature of the urethane film permits the dressing to conform to virtually any contour of the patient's skin at the location where the dressing is applied. The flexibility and thinness of the urethane film, however, present the problem of applying the wound dressing to the patient without stretching the urethane film. Stretching of the dressing prior to or during application to a patient may momentarily expand the stretchable urethane film and, even though the dressing may appear smooth when applied to the patient it will very quickly contract after the stretching forces are relieved, thereby causing discomfort to the patient and irritation to the area surrounding the wound. On weak or damaged skin, as in the elderly, the stretching forces may even cause abscesses or other skin damage.
One proposed solution to the stretching problem has been to use heavier or thicker urethane films. Unfortunately, heavier urethane films are undesirable as a wound dressing due to decreased flexibility and less gas permeability. Many conventional urethane films are about 1.0 mil or more thick. Although thinner urethane films will achieve greater gas permeability, moisture vapor transmission rates and increased flexibility and comfort, use of such thin films has been unsuccessful because they are relatively fragile and consequently difficult to work with during manufacture and assembly of the wound dressing.
Another proposed solution to this problem is to attach a flexible but non-stretching backing sheet to the urethane film using adhesive. The backing sheet remains in contact with the urethane film while the dressing is being applied to the patient, thereby eliminating stretching during application of the dressing. After the wound dressing has been attached to the patient, the backing sheet is subsequently peeled from the urethane film. Unfortunately, methods using adhesive to attach the urethane film to conventional backing sheets have been unable to handle the fragile and thin urethane films.
Another problem encountered when applying the polyurethane film to the wound is maintaining the sterility of the dressing during the application process. Previous products such as a polyurethane film wound dressings Ensure-IT (Deseret Medical, Inc.) and POLYSKIN.RTM. transparent dressing (Kendall Company, Boston, Mass.) required contact between fingers and the adhesive surface of the polyurethane film during application. It will be appreciated that such contact is undesirable as it may potentially contaminate the urethane film.